What is avian flu?

This is a contagious disease caused by various strains of flu viruses. It is common in birds, which suffer like humans and mainly recover, especially if the virus is a low pathogenic strain. Even in some high pathogenic strains, such as H5 and H7, which usually prove fatal in birds, some birds survive. Some species of wild geese and duck show no symptoms at all. It can also affect dogs and cats, pigs, horses and sometimes humans.

Why is the H5N1 strain of avian flu so different?

This is the most dangerous form of the virus known so far and can be transmitted by birds to humans in close contact with them. There are four separate strains of this lethal virus and the one of most concern is the high pathogenic Asian strain.

Since 2003 the disease has spread from Asia to Europe and Africa and, of the 335 humans who have become infected by the virus, 206 have died. Most have been poultry workers or keepers who have contracted the virus by breathing in particles from dried infected bird faeces.

There is some evidence of human-to-human transmission of the virus but not yet to trigger a pandemic. It is thought a girl in Thailand passed the virus to her mother and in 2004 two sisters died possibly from bird flu after their brother died of an unknown respiratory disease. There have been other cases where members of the same family have died but their infection is believed to be linked to living in close proximity to poultry.

This deadly flu is still essentially a disease of birds. In chickens and turkeys it can wipe out flocks. About 150 million birds worldwide have been killed by the virus in the past four years. It can also destroy ducks and geese, though some of these farmed birds appear to be more resilient to the strain. In the wild there are some ducks and geese that can carry the virus without showing any signs of sickness. In parts of South-East Asia the virus is endemic in the wild bird population.

What are the implications of this outbreak occurring among free-range birds?

The main question is whether there can be a long-term future for farmers to rear their birds outdoors. This is a particular concern to free-range and organic farmers who receive a cash premium from supermarkets.

Consumers like buying and eating free-range and organic birds because they believe that the birds lived a more natural life instead of being housed indoors in relatively cramped spaces.

It may be that free-range and organic farmers will have to lock up their birds during the autumn and spring migration periods to safeguard their livelihood.

Ultimately, it is a commercial risk but consumers will probably remain loyal to these farmers and will remain willing to pay higher prices for premium birds.

Farmers keeping birds for free-range meat and eggs, however, should ensure that they have housing for birds and, at migration times, should at the least do everything possible to keep poultry away from wild birds — erecting wire mesh enclosures for example, and preventing the mingling of poultry with wild birds at lakes or ponds.

A UK poultry industry that is confined entirely indoors may be inevitable, however, if a flu pandemic occurs because consumers will not wish farmers to take any risks.

What could be the impact on the poultry industry from this new Suffolk outbreak?

The immediate threat is to the Christmas turkey market, which is valued at £400 million in the UK. About a third of the 17 million birds reared in the UK each year are raised in East Anglia. About 10 million birds are consumed at Christmas so that means just over 3 million East Anglian birds are being reared for the festive celebrations. Farmers are already suffering from the restrictions involved in fighting foot and mouth disease and bluetongue. Many farms have tight cash flows and, if this virus spread, many would face severe financial hardship and some would have to quit the business.

What are the likely sources of contamination?

The jury is still out on the cause of this latest outbreak. But the strain in Suffolk is almost the same as that found in outbreaks in southern Germany and the Czech republic at the end of August and early September.

Across the world most transmission has been linked to international trade in poultry. The H5N1 outbreak at Bernard Matthews in Holton, Suffolk, was thought first to have been caused by wild birds. Scientific geno-typing of the strain, however, found it was an almost identical match to the outbreak in Hungary at the beginning of the year. Bernard Matthews has close business links and imports imported turkeys from Hungary to Suffolk but no clear proof of the cause was ever established. There is not thought to be a direct link between the Bernard Matthews case and the free-range Redgrave Park Farm, near Diss.

In this latest case it is known that young chicks were brought on to the Suffolk farm from the Netherlands about a month ago. Veterinary epidemiologists are now tracking every movement of lorry, bird crate, drivers, farm staff and any other equipment to see if there is any link with outbreaks on the continent. Live virus can be picked up from dried faeces on tyres, footwear, crates, birds or feathers.

It is possible this time, however, that wild birds or just one rogue infected bird is the problem. The concern inside the Government, however, is because poultry appears to have been allowed to mingle with wild birds at an ornamental lake on the farm. If this is established it would not take long for this to spread in wild birds generally. It is curious that during a period when tests on wild birds have been stepped up, not one bird has been found with this avian flu and there have been no sightings of groups of dead birds.

Why are government vets warning that the virus could be endemic in the wild bird population?

Once in wild birds, farmers would have to live with the disease and take the commercial risk of rearing their birds outdoors. There would be sporadic outbreaks but it would still be a disease of birds not humans.

Health chiefs and ministers would inevitably attempt to calm nerves of the population. Nevertheless, human nature being as it is, many people may prefer to keep their dogs and cats away from wild birds. Some would only walk dogs on a lead in open spaces near lakes or ponds, and some parents may stop children feeding the ducks or playing near water or in places with large gatherings of birds.

There may also be an initial downturn in poultry consumption but, as the Food Standards Agency has made clear, there is no risk to human health from eating poultry infected with the virus, provided that the bird is cooked thoroughly until juices run clear. The virus is killed by thorough cooking. Some people will prefer not to take any risk but as was shown in the UK during the BSE crisis that consumers in the UK are resilient, and while some refused to eat beef, others carried on regardless with roast beef dinners and steaks.

A solution eventually must be in the development of a vaccine to protect birds from this deadly virus.

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